Description

An area is an empty element holding information
about a region in a graphic, program listing, or screen.

The region is generally decorated with a number, symbol, or other
distinctive mark. The mark is usually used as the label for the
callout in a calloutlist, which
allows the reader to identify which callouts are associated with which
regions. The marks may be generated by the processing application from
the areas, or it may be added by some other process.
(This is an interchange issue. See Appendix D, Interchanging DocBook Documents.)

The coords, which are
required, identify the location of the region. The coordinates are
CDATA; how they are interpreted depends on the
units specified:

calspair

The coordinates are expressed using the semantics of the
CALS graphic attributes. The format of the
coordinates is “x1,y1 x2,y2”. This identifies a rectangle with
the lower-left corner at (x1,y1) and the upper-right corner at
(x2,y2). The x and y
coordinates are integers in the range 0 to 10000; they express a
percentage of the total distance from 0.00 to 100.00%. The
lower-left corner is (0,0).

linecolumn

The coordinates are expressed using lines and columns. The
format of the coordinates is “line column.” In a graphic
context, the meaning of this unit is unspecified.

linerange

The coordinates are expressed using lines. The format of
the coordinates is “startingline endingline.” In a graphic
context, the meaning of this unit is unspecified.

linecolumnpair

The coordinates are expressed as a continuous flow of
characters. The format of the coordinates is “line1 col1 line2
col2”. This identifies a flow of characters that begins at col1
of line1 and extends to col2 of line2. If line1 and line2 are
different, then the region includes all of the intervening lines
(including text that occurs before col1 and after col2). In
other words, this unit does not specify a rectangle. In a
graphic context, the meaning of this unit is unspecified.

otherunits

If specified, then the otherunits attribute is expected to
identify the units in some implementation-specific
way.

The units attribute is not
required; if it is not specified, the semantics of the coordinates
must be inherited from the surrounding areaspec or
areaset element or implied in some
implementation-specific manner.

In processing systems in which the mark is inserted
automatically, the label
attribute is provided as a mechanism for specifying what the mark
should be.

The author may point to any relevant information with linkends. DocBook does not specify a
semantic for these links. One possible use would be for providing a
link back to the appropriate callout in an online
environment.